<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		*{
			padding: 0;
			margin: 0;
		}
		body{
			
		}
		.box1{
			width:100px;
			height:100px;
			background-color:red;
			position: absolute;
			z-index: 100;
		}
		.box2{
			width:200px;
			height:200px;
			background-color:blue;
			position: absolute;
			z-index: 0;
		}
	</style>
</head>
<body>
	<div class="box1"></div>
	<div class="box2"></div>
</body>
</html>